Yes, it is possible in Linux.
Yes, it is possible in Linux.
You're right to be cautious. Reporting ACPI data frequently won't heavily impact a modern CPU. You can verify this using tools like htop or similar programs that show real-time usage. For example, the Acpid wiki page provides more details. Just make sure you're monitoring changes over time—30 seconds or a minute is enough to notice significant shifts. If your battery level drops quickly with those updates, it might be worth replacing it.
I mentioned earlier there might be a kernel-level power event you can follow. If not, I’d recommend a more cautious method. The battery level won’t shift noticeably in just one second. When the app launches, check the current battery percentage and how long it should last. Use that info to guess when the next drop of 1% will happen. Apply that timing to decide when to ask again. While doing this, compare your expected change with the actual change, then tweak how often you check. Run all these steps in the background quietly—only refresh the display when there’s a real update.
At some stage, it makes sense to think your laptop handles countless billions of operations each second. Billion by itself is a huge number. When you look at the work you put in to preserve just a few of them, it’s impressive. Your body uses energy for every movement you make. We’re getting into tiny details here.